25 Oct
2016
25 Oct
'16
4:30 p.m.
On 10/25/2016 01:28 PM, Fons Adriaensen wrote:
Or just have a script that tries to start jack, fails, waits a bit and
tries again (replacing jackd - a nasty hack).
It would be best to not depend on the web interface as that might not be
always available when we connect through usb.
I have not looked at the jack source to try to figure out why it is not
working while aplay does - maybe the card no longer generates
interrupts? Also, if the clock somehow changes while jack is running
(for example I disconnect the clock source if slaving to external
clock), jack goes into la-la land and we need to quit everything and
restart it to get things going again. Too bad...[*]
-- Fernando
[*] eventually I want to get these cards working with AVB...
On Tue, Oct 25, 2016 at 12:49:44PM -0700, Fernando
Lopez-Lezcano wrote:
Just using aplay alone... it plays "fine" except that it takes a few
seconds for sound to actually appear in the outputs.
When using aplay to help debug this it turns out
that aplay does not
complain, and it happily plays the soundfile, but nothing comes out
of the speakers for the first few seconds - I presume until the card
switches sampling rate.
Is that sampling rate actually set by aplay, or before by using HW
controls ? Once the
sampling rate has been defined at least _once_ then Jack
has no problem to start (over and over again) and aplay plays files
with sound from the beginning.
If you access the status and configuration web server in the Motu
you can switch the sampling rate and you see the clock lock icon
turn blinking red and then solid white once the change is done.
Also, alsamixer and amixer show a single read only "control" that is
actually the lock status indicator (the lsusb descriptors also show
another r/w control that can be used to _set_ the frequency but that
is somehow not reflected in the alsamixer/amixer interface).
A few lines of python could probably set the sample rate using the
web interface, wait until the card is ready, then start Jack.
Or find out what's required on the usb endpoint that sets the
sample rate.